Manufacture of zinc-white.



PATBNTED SEPT. 27, 1904.

J. OBTTLI. MANUFACTURE OF ZINC WHITEL APPLICATION IIL ED JULY 6, 1903.

N0 MODEL.

INVENTOR i614 ATTORNEYS UNITED STATES Patented September 27, 1904.

PATENT OFFICE.

JACQUES OETTLI, OF LAUSANNE, SWITZERLAND, ASSIGNOR TO THE FIRM OF SYNDIOAT POUR LEXPLOITATION DES INVENTIONS DU PROFES- SEUR OETTLI, OF BERNE, SWITZERLAND.

MANUFACTURE OF ZINC-WHITE.

SPECIFICATION forming part of Letters Patent No. 771,025, dated September 27, 1904. Application filed ly 6,1903. Serial No. 164,266. (No specimens.)

To all whom, it may concern..-

1 Zinc-white or oxid of zinc, (ZnO,) which con-' sists in subjecting Zinc plates to the action of-electrolysis in a heated alkaline bath, as will be more fully described hereinafter, and finally pointed out in the claim.

I In order to obtain oxid of zinc by means of electrolysis, according to this invention a warm solution of sulfate of soda (NazSOi) (or of any other alkali metal salt of an acid of which the Zinc salt is soluble) is electrolyzed by means 0 of electrodes formed of sheets of zinc. This forms at the anode sulfate of zinc (or other soluble zinc salt) and at the cathode soda, (or other soluble alkali.) The soda or alkali throws down hydroxid of Zinc, Zn(OH2,) from the hot 2 5 solution of the zinc salt, and this hydroxid of zinc being insoluble in water is then separated from the solution by filtration, drying, or otherwise and. is afterward calcined, thus forming anhydrous oxid of Zinc (ZnO) or zinc- 3 white. The chemical reactions are as follows:

- 2Na2SOi: 4Na+2SOi by electrolysis.

fNa-l- 4H2O I 4NaOH 4H.

2804+ QZn I 2ZnS Oi. 4NaOH+ QZnSO; I 2Na2SOi+ 2Zn(OH)2. 2Zn(OH)2 2ZnO+ 2H2O.

with an electric current of ten amperes per The temperature of the bath in which the oxid of Zinc is obtained square decimeter grows quickly to O., and this temperature is maintained by means of 5 causing the electrolyte to circulate in the tanks. Produce: one amp. hour, 3.0 gr. ZnSO4, three gr. ZnSOl, 1.5 gr. ZnO, from which it is calculated that to obtain a ton of zinc-white in twenty-four hours there should be 74 KV. 5 5 equal to 96 electrical H. P. w

The accompanying drawing shows by way of example a diagrammatic view of the installation for carrying the method into practice, and although said drawing shows only four 60 electrolytic tanks in practice the said tanks are preferably grouped in three series of ten tanks each. In both cases two of the said series work together and one of them is out of 1 operation. 6 5

a is the distributing-tank of electrolyte, containing a solution of alkaline saltfor instance, sulfate of soda--and 6 represents the electrolytic tanks.

0 is a distributing-pipe, having taps 0 ar- 7 ranged above each tank 6.

Each tank Z) is provided with a siphon Z), adapted to exhaust from the bottom of the tank the liquid loaded with zinc-white and conduct it into a channel (Z, from which it 75 flows into a hydro-extractor a. The shaft f of the latter is rotated by any suitable means, and the liquid flowing into the tank a of the hydro-extractor then runs into a tank g, from which a pump it, also actuated by a suitable motor, exhausts the liquid through a pipe 2' and pumps it back through the pipe k into the distributing-tank a'.

The zinc electrodes Z are preferably in the form of superposed blades of a thickness of 5 one cm. and having a surface of 1 m They are connected together and with the electric circuit, as shown in the drawing, said electrical circuit being provided in case of a distribution with continuous current with areversing-com- 9 mutator of suitable kind.

The removal of the water from the hydrated oxid of zinc is effected in any appropriate muffle or the like.

I claim The process herein described of making zinc- White, which consists in subjecting zinc plates my invention I have signed my name in presto the action of electrlolysis in a solution of once of two subscribing Witnesses. one per cent. sodium su fate of a temperature a of approximately 60 C. obtained by means of JACQUES OETTLLI a current of ten amp. per square dec'imeter, substantially as described.

In testimony that I claim the foregoing as WVitnes'ses:

G. IMER, L. H. MUNIER. 

